Go with the Warne one piece Picatinny rail. It will interface with more high quality rings. Weaver and Picatinny rails are not the same dimensions.
Also, take the time and set up right. Get all your screws torqued down correctly and lap your rings. I use the Kokopelli Products lapping/accurizing kits, and think they are the best I've tried.
You are going to like your rifle. I have a 12FVSS in .223 and it is scary accurate (but only with light bullets). Mine is topped with a MeoPta 4-16x44. When I got mine I went with the Warne steel 2 piece bases because the one piece was out of stock. It does allow for easier loading, but I'd rather have the rigidity of the one piece base.